the nature and variety of living organisms Flashcards
what characteristics do living organisms share?
- M: they move
- R: they respire
- S: they respond to their Surroundings
- G: they grow and develop
- R: they reproduce
- E: they excrete their waste
- N: they require nutrition
- C: they control their internal conditions
describe the common features shown by plants (eukaryotic organism)
- multicellular
- cells contain chloroplasts, able to do photosynthesis
- cellulose cell walls
- store carbs as starch or sucrose
examples of plants?
flowering plants, such as a cereal (e.g. maize) and a herbaceous legume (e.g. peas/beans)
describe the common features shown by animals (eukaryotic organisms)
- multicellular
- no chloroplasts in cells, not able to do photosynthesis
- no cell walls
- usually have nervous co-ordination & able to move from one place to another
- often store carbs as glycogen
examples of animals
mammals (e.g. humans) and insects (e.g. housefly and mosquito)
describe common features shown by fungi (eukaryotic organism)
- not able to do photosynthesis
- body usually organised into a mycelium made from thread-like structures called hyphae, which contain many nuclei
- some examples single-celled
- cell walls made of chitin
- feed by saprotrophic nutrition
- may store carbs as glycogen
definition of saprotrophic nutrition?
feeding by extracellular secretion of digestive enzymes onto food material & absorption of the organic products
examples of fungi
mucor has typical fungal hyphae structure, and yeast (single celled)
describe common features shown by protoctists (eukaryotic organisms)
- microscopic single celled organisms
- some have features like an animal cell (like amoeba, which live in pond water)
- others have chloroplasts & more like plants (like chlorella)
- pathogenic example: plasmodium, causes malaria
examples of protoctists
- amoeba: live in pond water, features like animal cell
- chlorella: chloroplasts, more like plants
- plasmodium: pathogenic, causes malaria
describe the common features shown by prokaryotic organisms such as bacteria
bacteria:
- microscopic single celled organisms
- have cell wall, cell membrane, cytoplasm, plasmids
- lack nucleus but contain circular chromosome of dna
- some can do photosynthesis but most feed off dead/living organisms
examples of bacteria
- lactobacillus bulgaricus: rod-shaped bacterium used in production of yoghurt from milk
- pneomococcus: spherical bacterium that acts as pathogen causing pneumonia
what are eukaryotes?
organisms whose cells contain a proper nucleus - a membrane sphere containing linear chromosomes of DNA. they all also have other organelles with outer membranes, e.g. mitochondria
what’s a prokaryote
organisms that don’t have a proper nucleus, instead the genetic material is in the cytoplasm in the form of a single circular chromosome
what are pathogens?
microorganisms which cause infectious disease, they harm the host by releasing toxins or damaging cells.
all viruses are pathogens, and bacteria, fungi, & protoctists can also be pathogens.
what are characteristics of viruses?
- not living organisms
- small particles, smaller than bacteria
- parasitic & can only reproduce inside living cells
- infect every type of living organism
- have wide variety of shapes & sizes
- have no cellular structure but have protein coat & contain 1 type of nucleic acid (DNA or RNA)
what are examples of viruses?
- tobacco mosaic virus that causes discolouring of leaves of tobacco plants by preventing formation of chloroplasts
- influenza virus that causes ‘flu’
- HIV virus that causes AIDS
what are bacteria’s cell walls made of?
peptidoglycan (a complex molecule of sugars and proteins)
what are fungi’s cell walls made of?
chitin
what are plants cell walls made of?
cellulose
